As a technique in this field, there is Japanese Unexamined Patent Application Publication No. 2007-85909. Japanese Unexamined Patent Application Publication No. 2007-85909 discloses an apparatus for detecting the position of another vehicle. The apparatus calculates an error in the GPS position information of a host vehicle in advance, using map matching between the GPS position information of the host vehicle and map information. When the GPS position information of another vehicle is acquired, the apparatus estimates the calculated error as an error in the GPS position information of another vehicle and corrects the error. In this way, it is possible to rapidly detect the position of another vehicle.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2007-85909